Detergent compositions in tablet form are known in the art. It is understood that detergent compositions in tablet form hold several advantages over detergent compositions in particulate form, such as ease of dosing, handling, transportation and storage.
Detergent tablets are most commonly prepared by pre-mixing components of a detergent composition and forming the pre-mixed detergent components into a tablet using any suitable equipment, preferably a tablet press. Tablets are typically formed by compression of the components of the detergent composition so that the tablets produced are sufficiently robust to be able to withstand handling and transportation without sustaining damage. In addition to being robust, tablets must also dissolve sufficiently fast so that the detergent components are released into the wash water as soon as possible at the beginning of the wash cycle.
However, a dichotomy exists in that as compression force is increased, the rate of dissolution of the tablets becomes slower. A low compression force, on the other hand, improves dissolution but at the expense of tablet strength. This problem is compounded by the fact that conventional tablet compositions have relatively poor long-term storage-stability characteristics and, to compensate, have to be manufactured to a higher compression specification. The present invention therefore seeks to provide tablet compositions having improved tablet dissolution characteristics and which at the same time delivers excellent long-term storage-stability characteristics in terms of strength and robustness.
Polymeric disintegrants and water-soluble hydrated salts such as sodium acetate trihydrate are well-known components of tablet compositions. It has now been discovered, however, that mixtures of polymeric disintegrants of defined particle size distribution together with certain water-soluble hydrated salts are particularly beneficial for improving the dissolution behaviour of detergent tablets whilst at the same time providing excellent strength and robustness characteristics during long-term storage.
The present invention therefore provides single and multi-phase detergent tablets for use in automatic dishwashing, laundry, etc and which display improved dissolution, strength and long-term storage characteristics. Tablet compositions formulated for use in automatic dishwashing machines are particularly preferred herein.